Phenyl and fluorenyl substituted phenyl-pyrazole complexes of Ir
申请人:The University of Southern California
公开号:US10741775B2
公开(公告)日:2020-08-11
The invention provides emissive materials and organic light emitting devices using the emissive materials in an emissive layer disposed between and electrically connected to an anode and a cathode. The emissive materials include compounds with the following structure:
wherein at least one of R8 to R14 is phenyl or substituted phenyl, and/or at least two of R8 to R14 that are adjacent are part of a fluorenyl group. The emissive materials have enhanced electroluminescent efficiency and improved lifetime when incorporated into light emitting devices.
Blue and Near-UV Phosphorescence from Iridium Complexes with Cyclometalated Pyrazolyl or <i>N</i>-Heterocyclic Carbene Ligands
作者:Tissa Sajoto、Peter I. Djurovich、Arnold Tamayo、Muhammed Yousufuddin、Robert Bau、Mark E. Thompson、Russell J. Holmes、Stephen R. Forrest
DOI:10.1021/ic051296i
日期:2005.10.1
Two approaches are reported to achieve efficient blue to near-UV emission from triscyclometalated iridium(III) materials related to the previously reported complex, fac-lr(ppz)(3) (ppz = 1-phenylpyrazolyl-N,C-2'). The first involves replacement of the phenyl group of the ppz ligand with a 9,9-dimethyl-2-fluorenyl group, i.e., fac-tris(1-[(9,9-dimethyl-2-fluorenyl)]pyrazolyl-N,C-2')iridium(III), abbreviated as fac-lr(flz)(3). Crystallographic analysis reveals that both fac-lr(flz)3 and fac-lr(ppz)(3) have a similar coordination environment around the Ir center. The absorption and emission spectra of fac-lr(flz)(3) are red shifted from those of fac-lr(ppz)(3). The fac-lr(flz)(3) complex gives blue photoluminescence (PL) with a high efficiency (lambda(max) = 480 nm, phi(PL) = 0.38) at room temperature. The lifetime and quantum efficiency were used to determine the radiative and nonradiative rates (1.0 x 10(4) and 2.0 x 10(4) s(-1), respectively). The second approach utilizes N-heterocyclic carbene (NHC) ligands to form triscyclometalated Ir complexes. Complexes with two different NHC ligands, i.e., iridium tris(1-phenyl-3-methylimidazolin-2-ylidene-C,C-2'), abbreviated as Ir(pmb)(3), and iridium tris(l-phenyl-3-methylbenzimidazolin-2-ylidene-C,C-2'), abbreviated as Ir(pmb)3, were both isolated as facial and meridianal isomers. Comparison of the crystallographic structures of the fac- and mer-isomers of lr(pmb)(3) with the corresponding Ir(ppz)(3) isomers indicates that the imidazolyl-carbene ligand has a stronger trans influence than pyrazolyl and, thus, imparts a greater ligand field strength. Both fac-lr(pmi)(3) and fac-lr(pmb)(3) complexes display strong metal-to-ligand-charge-transfer absorption transitions in the UV (lambda = 270-350 nm) and phosphoresce in the near-UV region (E0-0 = 380 nm) at room temperature with phi(PL) values of 0.02 and 0.04, respectively. The radiative decay rates for fac-lr(pmi)(3) and fac-lr(pmb)(3) (5 x 10(4) s(-1) and 18 x 10(4) s(-1), respectively) are somewhat higher than that of fac-lr(flz)(3), but the nonradiative rates are two orders of magnitude faster (i.e., (2-4) x 10(6) s(-1)).
REGULATION OF A CONTROLLED RADICAL POLYMERIZATION OF ACRYLATES BY LIGHT
申请人:DOW GLOBAL TECHNOLOGIES LLC
公开号:US20170029535A1
公开(公告)日:2017-02-02
Disclosed are methods for controlled radical polymerization of acrylic monomers using photoredox catalyst, where the polymerization is mediated, as well as regulated, by light.